Preparing tetraethyl lead



United States Patent 3,057,898 PREPARING TETRAETHYL LEAD Laszlo F. Biritz, Chicago, 111., assignor, by mesne assignments, to Houston Chemical Corporation, New York, N .Y., a corporation of Texas No Drawing. Filed Nov. 24, 1961, Ser. No. 154,819 16 Claims. (Cl. 260-437) The present invention relates to a process for manufacturing tetraethyl lead.

Tetraethyl lead is a valuable compound which has been manufactured on a large scale for many years. It .is a relatively expensive material to manufacture. Accordingly, even slight improvements in yield, amounting to only a fraction of a percent, are important commercially and economically.

The conventional method for making a tetratethyl lead today follows the equation:

An, object. of the present invention is to provide a process of preparing tetraethyl lead which materially increases the speed of reaction without decreasing the yield.

Another object is to provide novel catalysts for the reaction of ethyl chloride with lead-monosodium alloy.

Still further objects and the entire scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

It has now been found that these objects can be attained by reacting a lead-sodium alloy with ethyl chloride in the presence of a small amount, e.g., 0.002l0% based on the mols of sodium in the lead-sodium alloy, of certain silicon, aluminum, titanium and zirconium compounds as set forth hereinafter.

While preferably lead-monosodium alloy is employed, there can be used other lead-sodium alloys such as Na Pb and Na Pb The sodium can be 20% of the alloy by weight. The ethyl chloride and lead-sodium alloy can be reacted on an equimolar basis. However, preferably an excess of the ethyl chloride is used, e.g., l.3- moles per mol of lead-monosodium alloy, to obtained better yields.

As accelerators according to the present invention there are employed compounds having the formulae where R R R and R are the same or different hydrocarbon or haloaryl groups. The preferred catalysts are the lower alkyl esters, most preferably the lower alkyl silicates.

Examples of suitable compounds within the above 3,057,898 Patented Oct. 9, 1962 formulae are tetramethyl orthosilicate, tetraethyl ortho silicate, methyl triethyl orthosilicate, dimethyl diethyl orthosilicate, tetrapropyl orthosilicate, tetraisopropyl orthosilicate, tetrabutyl orthosilicate, tetra secondary butyl orthosilicate, tetra tertiary butyl orthosilicate, tetrahexyl orthosilicate, tetracyclohexyl orthosilicate, tetradodecyl orthosilicate, tetravinyl orthosilicate, tetraallyl orthosilicate, tetramethallyl orthosilicate, tetrabenzyl silicate, tetraphenyl orthosilicate, tetra o-tolyl orthosilicate, tetra p-tolyl orthosilicate, tetra m-tolyl orthosilicate, tetra pbutylphenyl orthosilicate, tetraxylyl orthosilicate, tetra o-chlorophenyl orthosilicate, tetra p-bromophenyl orthosilicate, tetra a-naphthyl orthosilicate, tetra B-naphthyl orthosilicate, aluminum trimethoxide, aluminum triethoxide, aluminum tripropoxide, aluminum triisopropoxide, aluminum tributoxide, aluminum trihexoxide, aluminum triphenoxide, aluminum tritoloxide, aluminum trichlorophenoxide, aluminum tricyclohexoxide, aluminum tri a-naphthoxide, aluminum tri ,B-naphthoxide, aluminum tribenzoxide, hexaethyl disiloxane, hexamethyl disiloxane, hexaisopropyl disiloxane, hexapropyl disiloxane, hexabutyl disiloxane, hexahexyl disiloxane, hexaphenyl disiloxane, hexa p-chlorophenyl disiloxane, tetramethyl titanate, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, tetrahexyl titanate, tetracyclohexyl titanate, tetraphenyl titanate, tetra ptolyl titanate, tetra p-chlorophenyl titanate, tetra ,B-naphthyl titanate, tetramethyl zirconate, tetraethyl Zirconate, tetrapropyl zirconate, tetraisopropyl zirconate, tetrabutyl zirconate, tetrahexyl zirconate, tetracyclohexyl zirconate, tetraphenyl zirconate, tetra p-tolyl zirconate, tetra a-naphthyl zirconate, tetra m-chlorophenyl zirconate.

The examples were carried out using the following conditions unless otherwise noted. A 150 ml. stainless steel bomb was purged with nitrogen (an inert atmosphere). Then 46 grams of lead-monosodium alloy (0.2 mol) of 12-24 mesh size were placed therein. The particle size of the alloy is conventional and is not critical. (Thus, it can be widely varied, e.g., from 4 to 300 mesh.) The bomb was evacuated to about 1 mm. or less and put in a Dry Ice-acetone bath and then there were condensed in the bomb grams of ethyl chloride. (This is a substantial excess of the ethyl chloride over theoretical and can be varied, for example, between 70 and grams, without significant change in yields.) The bomb was then pressured with nitrogen to 10 p.s.i. above atmospheric pressure. The catalyst (accelerator) was then put in the cold mixture and the bomb placed in a shaker bath maintained at about 70 C. It took about 3 minutes for the bomb to get bath temperature. In the examples, in recording the time, the time to reach bath temperature is included. Hence, the reaction time at the bath temperature was actually somewhat less than the time stated.

It may be noted that the temperature of reaction is not critical but can be varied, e.g., from 50-120 C.

In the examples total yield was obtained by determining the amount of sodium chloride formed and yield of tetraethyl lead (T.E.L.) was determined by iodine titration.

As previously indicated, in the examples the alloy employed was lead-monosodium alloy. The percent of catalyst in the examples is molar percent based on the moles of sodium in the alloy, e.g., if 2% catalyst is used in the example, there are 0.004 mol of catalyst r 3 (since 0.2 mol of alloy is employed in the examples unless otherwise noted).

Example 7 was the average of a series of control runs omitting the catalyst. It will be observed that it took over 10 minutes longer to obtain the same yield in the control runs as those with any of the catalyst of the present invention.

Example 8 In a plant run utilizing 0.05% of tetraethyl orthosilicate and a reaction temperature of 70 C. there was obtained an over-all yield of about 96% and a tetraethyl lead yield of about 76% in about 20 minutes. 46 pounds of ethyl chloride were used per 100 lbs. of leadmonosodium alloy.

Example 9 Utilizing 2% of tetraisopropyl zirconate in the bomb described in connection with Examples 1-7 there is obtained comparable yields of tetraethyl lead after 21 minutes at about 70 C.

Example 10 Utilizing 2% of tetraphenyl orthosilicate in the bomb described in connection with Examples 17 there is obtained comparable yields of tetraethyl lead after 20 minutes at about 70 0.

Example 11 Utilizing 2% of hexaethyl disiloxane in the bomb described in connection with Examples 1-7 there is obtained comparable yields of tetraethyl lead after 20 minutes at about 70 C.

The present invention can be carried out either batchwise or in continuous fashion.

I claim:

1. A process of preparing tetraethyl lead comprising reacting a lead-sodium alloy and ethyl chloride in the presence of a catalyst selected from the group consisting of compounds having the formulae 4 where R R R and R are selected from the group consisting of alkyl, allyl, vinyl, methallyl, benzyl, phenyl, alkyl, phenyl having up to 4 carbon atoms in the alkyl groups, naphthyl, chlorophenyl and bromophenyl.

2. A process according to claim 1 wherein the catalyst is present in an amount of 0.002-10 mol percent based on the sodium in the alloy.

3. A process according to claim 2 wherein the leadsodium alloy is lead-monosodium alloy and the ethyl chloride is used in an amount in excess of that required to react with the alloy.

4. A process of preparing tetraethyl lead comprising reacting a lead-sodium alloy and ethyl chloride in the presence of a tetrahydrocarbon orthosilicate as a catalyst, the hydrocarbon groups of said tetrahydrocarbon orthosilicate being selected from the group consisting of alkyl, allyl, vinyl, methallyl, benzyl, phenyl, alkyl phenyl having up to 4 carbon atoms in the alkyl groups and naphthyl.

5. A process according to claim 4 wherein the tetrahydrocarbon orthosilicate is a tetra lower alkyl orthosilicate.

6. A process of preparing tetraethyl lead comprising reacting a lead-sodium alloy and ethyl chloride in the presence of tetraethyl orthosilicate as a catalyst.

7. A process acording to claim 6 wherein the alloy is lead-monosodium alloy and the catalyst is used in an amount of 0.002-2 mol percent based on the sodium in the alloy.

8. A process of preparing tetraethyl lead comprising reacting a lead-sodium alloy and ethyl chloride in the presence of a hexahydrocarbon disiloxane as a catalyst, the hydrocarbon groups of said hexahydrocarbon disiloxane being selected from the group consisting of alkyl, allyl, vinyl, methallyl, benzyl, phenyl, alkyl phenyl having up to 4 carbon atoms in the alkyl groups and naphthyl.

9. A process according to claim 8 wherein the hydrocarbon groups are lower alkyl groups.

10. A process according to claim 8 wherein the catalyst is hexaethyl disiloxane.

11. A process of preparing tetraethyl lead comprising reacting a lead-sodium alloy and ethyl chloride in the presence of an aluminum trihydrocarbonoxide as a catalyst, the hydrocarbon groups of said trihydrocarbonoxide being selected from the group consisting of alkyl, allyl, vinyl, methalllyl, benzyl, phenyl, alkyl phenyl having up to 4 carbon atoms in the alkyl groups and naphthyl.

12. A process of preparing tetraethyl lead comprising reacting a lead-sodium alloy and ethyl chloride in the presence of an aluminum tri lower alkoxide as a catalyst.

13. A process according to claim 12 wherein the alkoxide is aluminum isopropoxide.

14. A process of preparing tetraethyl lead comprising reacting a lead-sodium alloy and ethyl chloride in the presence of a tetrahydrocarbon titanate as a catalyst, the hydrocarbon groups of said tetrabydrocarbon titanate being selected from the group consisting of alkyl, allyl, vinyl, methallyl, benzyl, phenyl, alkyl phenyl having up to 4 carbon atoms in the alkyl groups and naphthyl.

15. A process according to claim 14 wherein the titanate is a tetra lower alkyl titanate.

16. A process according to claim 15 wherein the titanate is tetraisopropyl titanate.

No references cited. 

1. A PROCESS OF PREPARING TETRARTHYL LEAD COMPRISING REACTING A LEAD-SODIUM ALLOY AND ETHYL CHLORIDE IN THE PRESENCE OF A CATALYST SELECTED FROM THE GROUP CONSISTING OF COMPOUNDS HAVING THE FORMULATE 